Effects Of Different β-Carotene Level On Milk Yield And Milk Quality Of Dairy Cows

The purpose of this experiment was studying the effect of adding differentβ–carotene content on cow's milk production quantity and the dairy product quality. 32 Australian Holland Stan cow which had the same age, the body weight, the nutrition condition and the embryo time for firstborn were selected. Using the completely randomized block design, the cows were divided into 4 treatment groups, and each treatment group had 8 repetitions. The foundation date grain was composed of silage corn, alfalfa grass powder, small wheat straw and concentrated feed.4 processing components are: I group for comparison group (foundation date grain);II group(foundation date grain +β–carotene 30mg/d/cow);Ⅲgroup(foundation date grain +β–carotene 60mg/d/cow,Ⅳgroup(foundation date grain +β–carotene 90mg/d/cow).The experimental time was 70 days, protesting time was 10 days, testing time was 60 day. The daily milk production quantity were recorded, the blood samples and milk samples were taken periodically, dairy quality were tested, andβ–carotene content in blood and milk were tested by HPLC.The results showed that the milk production of comparison group was increased, the milk production of other groups were increased first and then decreased. After addingβ–carotene for 20 days, the milk production betweenⅣgroup and comparison group showed significant different at 0.05 level(P<0.05),the milk production ofⅣgroup was increased 11.03% than comparison group, After addingβ–carotene for 40 days, the milk production ofⅣgroup was increased 13.83% than comparison group ,which showed significant different at 0.05 level(P<0.05).After addingβ–carotene for 60 days, the different among four groups were not significant.( P>0.05)In the milk quality aspect, the butter content of II group increased 5.13% compared with comparison group, and showed significant different at 0.05 level.ⅢandⅣgroups showed significant different at 0.01 level, increasing 6.34% and 9.36%. The milk protein betweenⅣgroup and comparison group showed significant different at 0.05 level(P<0.05), Compared with comparison group,Ⅳgroups increased 2.05%.There were not significant different among every treatment groups(P>0.05).Theβ–carotene content in blood were not significant different among the four groups(P>0.05)before addingβ–carotene,60 days later , II group increased 38.55% compared with comparison group.Ⅲgroup increased 99.24%,showing significant different at 0.01 level (P<0.01).Meanwhile, compared with II group,Ⅲgroup had a tendency to increase.Ⅳgroup increased 122.85% compared with comparison group, which showed significant different at 0.01 level ,and increased 60.84% compared II group.After addingβ–carotene for 60 days, theβ–carotene content in milk showed significant different at 0.05 level among four groups. Compared with comparison group, theβ–carotene content of II group,Ⅲgroup andⅣgroup were improved 63.27%,148.46% and 262.29%.They all showed significant different at 0.01 level.The results showed that: addingβ–carotene in daily feed of cow could improve the milk production quantity greatly, and keep the milk production on a higher extent. Meanwhile it could improve theβ–carotene content in blood, which can change the health condition of cow and contribute to decline the chance of mastitis. It could also improve the milk quality, increased theβ–carotene content in milk and improve the nutrition of milk. It had a important value and wonderful foreground in feeding areas where cow were fed with Wheat Straw .